Tony Wendice was a total sleaze
Glad to see so many comments still about this film after so many years, it is one of my Hitchcock favorites too. Always strikes me at the end when Tony opens the door and realizes his mistake, then there is the hint that "he might try to run for it", until he notices the other detective. How much sleazier than that can you get ?? That look of disgust from Margo is exactly what he deserves.
RSGRE